The objective of this study is to gain an understanding of the mortality patterns among men who had a vasectomy performed a minimum of fifteen years in the past. Although cohort studies have not shown an association between vasectomy and mortality, these studies have generally had short follow-up periods. This study will identify a cohort of men who had a vasectomy at least fifteen years ago, a similarly sized suitable control group, and analyze the mortality patterns among these two groups of men for differences. Specific causes-of-death of interest include atherosclerosis, cancer, all cardiovascular disease and diseases of the immune system. Concomitant variables will be ascertained for appropriate control of confounders.